/*******************************************************************************
 * Copyright IBM Corp. and others 2000
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include "codegen/BackingStore.hpp"
#include "codegen/CodeGenerator.hpp"
#include "codegen/ConstantDataSnippet.hpp"
#include "env/FrontEnd.hpp"
#include "codegen/Instruction.hpp"
#include "codegen/Linkage.hpp"
#include "codegen/Linkage_inlines.hpp"
#include "codegen/LiveRegister.hpp"
#include "codegen/Machine.hpp"
#include "codegen/Machine_inlines.hpp"
#include "codegen/MemoryReference.hpp"
#include "codegen/RealRegister.hpp"
#include "codegen/Register.hpp"
#include "codegen/RegisterConstants.hpp"
#include "codegen/RegisterDependency.hpp"
#include "codegen/RegisterRematerializationInfo.hpp"
#include "codegen/RegisterUsage.hpp"
#include "codegen/TreeEvaluator.hpp"
#include "compile/Compilation.hpp"
#include "control/Options.hpp"
#include "control/Options_inlines.hpp"
#include "env/CompilerEnv.hpp"
#include "env/IO.hpp"
#include "env/ObjectModel.hpp"
#include "env/TRMemory.hpp"
#include "il/Block.hpp"
#include "il/DataTypes.hpp"
#include "il/ILOpCodes.hpp"
#include "il/ILOps.hpp"
#include "il/Node.hpp"
#include "il/Symbol.hpp"
#include "il/SymbolReference.hpp"
#include "infra/Assert.hpp"
#include "infra/List.hpp"
#include "ras/Debug.hpp"
#include "ras/Logger.hpp"
#include "x/codegen/OutlinedInstructions.hpp"
#include "codegen/X86Instruction.hpp"
#include "codegen/InstOpCode.hpp"

extern bool existsNextInstructionToTestFlags(TR::Instruction *startInstr, uint8_t testMask);

#define IA32_REGISTER_HEAVIEST_WEIGHT 0x0000ffff
#define IA32_REGISTER_INTERFERENCE_WEIGHT 0x00008000
#define IA32_REGISTER_INITIAL_PRESERVED_WEIGHT 0x00001000
#define IA32_REGISTER_ASSOCIATED_WEIGHT 0x00000800
#define IA32_REGISTER_PLACEHOLDER_WEIGHT 0x00000100
#define IA32_REGISTER_BASIC_WEIGHT 0x00000080

#define IA32_REGISTER_PRESERVED_WEIGHT 0x00000002
#define IA32_BYTE_REGISTER_INTERFERENCE_WEIGHT 0x00000004

// Distance (in number of instructions) from the current instruction to search
// while looking for a spill candidate.
//
#define FREE_BEST_REGISTER_SEARCH_DISTANCE 800

// Distance (in number of instructions) from the current instruction before a
// register will be given priority as a spill candidate.
//
#define FREE_BEST_REGISTER_MINIMUM_CANDIDATE_DISTANCE 4

// Candidate register types for freeBestGPRegister
//
enum FreeBestRegisterCandidateTypes {
    BestNonInterferingDiscardableConstant = 0,
    BestMayInterfereDiscardableConstant,
    BestInterferingDiscardableConstant,
    BestNonInterferingDiscardableMemory,
    BestMayInterfereDiscardableMemory,
    BestInterferingDiscardableMemory,
    NonInterferingTarget,
    InterferingTarget,
    BestNonInterfering,
    BestMayInterfere,
    BestInterfering,
    NumBestRegisters
};

// Significant distances (in number of instructions) between candidate register
// types in freeBestGPRegister
//
static const int16_t freeBestRegisterSignificantDistances[NumBestRegisters][NumBestRegisters] = {
    { 0, 5, 10, 20, 20, 20, 40, 40, 60, 60, 60 }, // BestNonInterferingDiscardableConstant
    { 0, 0, 10, 20, 20, 20, 40, 40, 60, 60, 60 }, // BestMayInterfereDiscardableConstant
    { 0, 0,  0, 10, 20, 20, 30, 30, 50, 50, 50 }, // BestInterferingDiscardableConstant
    { 0, 0,  0,  0,  5, 10, 40, 40, 60, 60, 60 }, // BestNonInterferingDiscardableMemory
    { 0, 0,  0,  0,  0, 10, 40, 40, 60, 60, 60 }, // BestMayInterfereDiscardableMemory
    { 0, 0,  0,  0,  0,  0, 30, 30, 50, 50, 50 }, // BestInterferingDiscardableMemory
    { 0, 0,  0,  0,  0,  0,  0, 10, 40, 40, 90 }, // NonInterferingTarget
    { 0, 0,  0,  0,  0,  0,  0,  0, 10, 10, 90 }, // InterferingTarget
    { 0, 0,  0,  0,  0,  0,  0,  0,  0,  5, 20 }, // BestNonInterfering
    { 0, 0,  0,  0,  0,  0,  0,  0,  0,  0, 20 }, // BestMayInterfere
    { 0, 0,  0,  0,  0,  0,  0,  0,  0,  0,  0 }  // BestInterfering
};

bool existsNextInstructionToTestFlags(TR::Instruction *startInstr, uint8_t testMask)
{
    if (!startInstr)
        return false;

    TR::Instruction *cursor = startInstr;

    do {
        cursor = cursor->getNext();

        if (!cursor)
            break;

        // Cursor instruction tests an eflag that is set exclusively by our testMask.
        //
        if (cursor->getOpCode().getTestedEFlags() & testMask) {
            return true;
        }

        // Mask out those eflags that are modified by this instruction.
        //
        testMask = testMask & ~(cursor->getOpCode().getModifiedEFlags());
    } while (testMask && cursor->getOpCodeValue() != TR::InstOpCode::label
        && cursor->getOpCodeValue() != TR::InstOpCode::RET && cursor->getOpCodeValue() != TR::InstOpCode::RETImm2
        && cursor->getOpCodeValue() != TR::InstOpCode::retn && !cursor->getOpCode().isBranchOp());

    return false;
}

static bool registersMayOverlap(TR::Register *reg1, TR::Register *reg2)
{
    if (reg1->getStartOfRange() && reg2->getEndOfRange()
        && reg1->getStartOfRange()->getIndex() >= reg2->getEndOfRange()->getIndex())
        return false;
    if (reg1->getEndOfRange() && reg2->getStartOfRange()
        && reg1->getEndOfRange()->getIndex() <= reg2->getStartOfRange()->getIndex())
        return false;
    return true;
}

OMR::X86::Machine::Machine(uint8_t numIntRegs, uint8_t numFPRegs, TR::CodeGenerator *cg,
    TR::Register **registerAssociations, uint8_t numGlobalGPRs, uint8_t numGlobal8BitGPRs, uint8_t numGlobalFPRs,
    TR::Register **xmmGlobalRegisters, uint32_t *globalRegisterNumberToRealRegisterMap)
    : OMR::Machine(cg)
    , _registerAssociations(registerAssociations)
    , _numGlobalGPRs(numGlobalGPRs)
    , _numGlobal8BitGPRs(numGlobal8BitGPRs)
    , _numGlobalFPRs(numGlobalFPRs)
    , _xmmGlobalRegisters(xmmGlobalRegisters)
    , _globalRegisterNumberToRealRegisterMap(globalRegisterNumberToRealRegisterMap)
    , _spilledRegistersList(NULL)
    , _numGPRs(numIntRegs)
{
    self()->resetXMMGlobalRegisters();

    for (int i = 0; i < TR::NumAllTypes; i++) {
        _dummyLocal[i] = NULL;
    }

    self()->clearRegisterAssociations();
}

void OMR::X86::Machine::resetXMMGlobalRegisters()
{
    for (int32_t i = 0; i < TR::RealRegister::LastXMMR - TR::RealRegister::FirstXMMR + 1; i++)
        self()->setXMMGlobalRegister(i, NULL);
}

TR_Debug *OMR::X86::Machine::getDebug() { return self()->cg()->getDebug(); }

int32_t OMR::X86::Machine::getGlobalReg(TR::RealRegister::RegNum reg)
{
    for (int32_t i = 0; i < self()->getLastGlobalFPRRegisterNumber(); i++) {
        if (_globalRegisterNumberToRealRegisterMap[i] == reg)
            return i;
    }
    return -1;
}

TR::RealRegister *OMR::X86::Machine::findBestFreeGPRegister(TR::Instruction *currentInstruction, TR::Register *virtReg,
    TR_RegisterSizes requestedRegSize, bool considerUnlatched)
{
    int first, last, i;

    struct TR_Candidate {
        TR::Register *_virtual;
        TR::RealRegister::RegNum _real;
    } candidates[16]; // TODO:AMD64: Should be max number of regs of any one kind

    int32_t numCandidates = 0;

    TR_ASSERT_FATAL((virtReg
                        && (virtReg->getKind() == TR_GPR || virtReg->getKind() == TR_FPR || virtReg->getKind() == TR_VRF
                            || virtReg->getKind() == TR_VMR)),
        "OMR::X86::Machine::findBestFreeGPRegister() ==> Unexpected register kind!");

    bool useRegisterAssociations = self()->cg()->enableRegisterAssociations() ? true : false;
    bool useRegisterInterferences = self()->cg()->enableRegisterInterferences() ? true : false;
    bool useRegisterWeights = self()->cg()->enableRegisterWeights() ? true : false;

    if (useRegisterAssociations && virtReg->getAssociation() != TR::RealRegister::NoReg
        && self()->getVirtualAssociatedWithReal((TR::RealRegister::RegNum)virtReg->getAssociation()) == virtReg
        && (_registerFile[virtReg->getAssociation()]->getAssignedRegister() == NULL
            || (considerUnlatched
                && _registerFile[virtReg->getAssociation()]->getState() == TR::RealRegister::Unlatched))) {
        if (_registerFile[virtReg->getAssociation()]->getState() != TR::RealRegister::Locked) {
            if (requestedRegSize != TR_ByteReg || virtReg->getAssociation() <= TR::RealRegister::Last8BitGPR) {
                self()->cg()->setRegisterAssignmentFlag(TR_ByAssociation);
                return _registerFile[virtReg->getAssociation()];
            }
        }
    }

    switch (requestedRegSize) {
        case TR_ByteReg:
            first = TR::RealRegister::FirstGPR;
            last = TR::RealRegister::Last8BitGPR;
            break;
        case TR_DoubleWordReg:
#if defined(TR_TARGET_32BIT)
            TR_ASSERT_FATAL(0, "Unsupported register size");
#endif
        case TR_HalfWordReg:
        case TR_WordReg:
            first = TR::RealRegister::FirstGPR;
            last = TR::RealRegister::LastAssignableGPR;
            break;
        case TR_QuadWordReg:
        case TR_VectorReg128:
        case TR_VectorReg256:
        case TR_VectorReg512:
            // xmm/ymm/zmm are aliased
            first = TR::RealRegister::FirstXMMR;
            last = TR::RealRegister::LastXMMR;
            break;
        default:
            TR_ASSERT(0, "unknown register size requested\n");
    }

    if (virtReg->getKind() == TR_VMR) {
        TR_ASSERT_FATAL(cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F),
            "Cannot assign mask register on unsupported CPU");
        // k0 is reserved for unmasked operations
        first = TR::RealRegister::k1;
        last = TR::RealRegister::k7;
    }

    uint32_t weight;
    uint32_t bestWeightSoFar = IA32_REGISTER_HEAVIEST_WEIGHT;
    TR_RegisterMask interference = virtReg->getInterference();
    TR_RegisterMask byteRegisterInterference = interference & 0x80000000;
    TR::RealRegister *freeRegister = NULL;
    const TR::X86LinkageProperties &linkageProperties = self()->cg()->getProperties();

    for (i = first; i <= last; i++) {
        // Don't consider registers that can't be assigned.
        //
        if (_registerFile[i]->getState() == TR::RealRegister::Locked) {
            self()->cg()->traceRegWeight(_registerFile[i], 0xdead1);
            interference >>= 1;
            continue;
        }

        TR::Register *associatedRegister
            = useRegisterAssociations ? self()->getVirtualAssociatedWithReal((TR::RealRegister::RegNum)i) : NULL;

        if (useRegisterWeights) {
            if ((linkageProperties.isPreservedRegister((TR::RealRegister::RegNum)i)
                    || linkageProperties.isCalleeVolatileRegister((TR::RealRegister::RegNum)i))
                && _registerFile[i]->getWeight() == IA32_REGISTER_INITIAL_PRESERVED_WEIGHT) {
                if (associatedRegister)
                    _registerFile[i]->setWeight(IA32_REGISTER_ASSOCIATED_WEIGHT);
                else if (_registerFile[i]->getHasBeenAssignedInMethod())
                    _registerFile[i]->setWeight(IA32_REGISTER_BASIC_WEIGHT);
            }

            // Get the weight of the real register.
            //
            weight = _registerFile[i]->getWeight();

            // If the real register has an association whose live range does not
            // overlap with this one, make it very popular.
            //
            // Increase the weight if the register interferes with the virtual register.
            //
            if (associatedRegister && !registersMayOverlap(virtReg, associatedRegister))
                weight &= ~(IA32_REGISTER_ASSOCIATED_WEIGHT | IA32_REGISTER_PLACEHOLDER_WEIGHT);
            else if ((interference & 1))
                weight += IA32_REGISTER_INTERFERENCE_WEIGHT;

            // Add tie-breaking weights for preserved registers and for interference
            // with byte registers.
            //
            if (!(interference & 1)) {
                if (byteRegisterInterference && i <= TR::RealRegister::Last8BitGPR)
                    weight += IA32_BYTE_REGISTER_INTERFERENCE_WEIGHT;
                if (linkageProperties.isPreservedRegister((TR::RealRegister::RegNum)i))
                    weight += IA32_REGISTER_PRESERVED_WEIGHT;
            }
        } else {
            weight = _registerFile[i]->getWeight();
        }

        if (((_registerFile[i]->getAssignedRegister() == NULL
                 && _registerFile[i]->getState() != TR::RealRegister::Blocked)
                || (considerUnlatched && _registerFile[i]->getState() == TR::RealRegister::Unlatched))) {
            self()->cg()->traceRegWeight(_registerFile[i], weight);

            if (weight < bestWeightSoFar) {
                freeRegister = _registerFile[i];
                bestWeightSoFar = weight;
                numCandidates = 0;
            } else if (weight == bestWeightSoFar && useRegisterInterferences
                && (weight & IA32_REGISTER_INTERFERENCE_WEIGHT)) {
                TR::Register *r = self()->getVirtualAssociatedWithReal((TR::RealRegister::RegNum)i);
                if (r && (r->getAssociation() != TR::RealRegister::NoReg)
                    && _registerFile[i]->getState() == TR::RealRegister::Free) {
                    candidates[numCandidates]._virtual = r;
                    candidates[numCandidates++]._real = (TR::RealRegister::RegNum)i;
                }
            }
        } else if (_registerFile[i]->getAssignedRegister() == NULL)
            self()->cg()->traceRegWeight(_registerFile[i], 0xdead2);
        else
            self()->cg()->traceRegWeight(_registerFile[i], 0xdead3);

        interference >>= 1;
    }

    // If there is more than one interfering candidate, choose the one that
    // is used farthest away.
    //
    if (useRegisterInterferences && (numCandidates > 1)) {
        TR::Instruction *cursor;
        int32_t distance = 0;
        for (cursor = currentInstruction->getPrev(); cursor && numCandidates > 1; cursor = cursor->getPrev()) {
            if (cursor->getOpCodeValue() == TR::InstOpCode::proc)
                break;

            if (cursor->getOpCodeValue() == TR::InstOpCode::assocreg)
                continue;

            for (i = 0; i < numCandidates; i++) {
                if (cursor->refsRegister(candidates[i]._virtual)) {
                    self()->cg()->traceRegInterference(virtReg, candidates[i]._virtual, distance);
                    candidates[i] = candidates[--numCandidates];
                }
            }
            distance++;
        }
        freeRegister = _registerFile[candidates[0]._real];
    }

    return freeRegister;
}

TR::RealRegister *OMR::X86::Machine::freeBestGPRegister(TR::Instruction *currentInstruction, TR::Register *virtReg,
    TR_RegisterSizes requestedRegSize, TR::RealRegister::RegNum targetRegister, bool considerVirtAsSpillCandidate)
{
    TR::Register *candidates[16]; // TODO:AMD64: Should be max number of regs of any one kind
    int numCandidates = 0;
    int first, last;
    TR::Instruction *cursor;
    TR::Register *bestRegisters[NumBestRegisters];
    int32_t bestDistances[NumBestRegisters];
    TR::Register *bestRegister = NULL;
    int32_t bestDistance = -1;
    int32_t bestType = -1;
    int32_t distance = 1;
    TR_RegisterMask interference = virtReg->getInterference();
    TR_RegisterMask byteRegisterInterference = interference & 0x80000000;
    int32_t interferes;
    int32_t i, j;
    TR::RealRegister *realReg;

    TR::Compilation *comp = self()->cg()->comp();

    bool useRegisterInterferences = self()->cg()->enableRegisterInterferences() ? true : false;
    bool enableRematerialisation = self()->cg()->enableRematerialisation() && virtReg->getKind() != TR_VMR;
    // rematerialisation not supported for vector masks

    TR_ASSERT_FATAL(virtReg
            && (virtReg->getKind() == TR_GPR || virtReg->getKind() == TR_FPR || virtReg->getKind() == TR_VRF
                || virtReg->getKind() == TR_VMR),
        "OMR::X86::Machine::freeBestGPRegister() ==> expecting to free GPRs, VMRs or XMMRs only!");

    switch (requestedRegSize) {
        case TR_ByteReg:
            first = TR::RealRegister::FirstGPR;
            last = TR::RealRegister::Last8BitGPR;
            break;
        case TR_DoubleWordReg:
#if defined(TR_TARGET_32BIT)
            TR_ASSERT_FATAL(0, "Unsupported register size");
#endif
        case TR_HalfWordReg:
        case TR_WordReg:
            first = TR::RealRegister::FirstGPR;
            last = TR::RealRegister::LastAssignableGPR;
            break;
        case TR_QuadWordReg:
        case TR_VectorReg128:
        case TR_VectorReg256:
        case TR_VectorReg512:
            // xmm/ymm/zmm are aliased
            first = TR::RealRegister::FirstXMMR;
            last = TR::RealRegister::LastXMMR;
            break;
        default:
            TR_ASSERT_FATAL(0, "unknown register size requested\n");
    }

    TR::InstOpCode::Mnemonic vmrSpillOpcode;
    int32_t vmrStoreSize;

    if (virtReg->getKind() == TR_VMR) {
        first = TR::RealRegister::k1;
        last = TR::RealRegister::k7;
    }

    char *bestRegisterTypes[NumBestRegisters] = { "non-interfering discardable (from constant) register",
        "may interfere discardable (from constant) byte register", "interfering discardable (from constant) register",
        "non-interfering discardable (from memory) register", "may interfere discardable (from memory) byte register",
        "interfering discardable (from memory) register", "non-interfering target register",
        "interfering target register", "non-interfering register", "may interfere byte register",
        "interfering register" };

    if (targetRegister)
        self()->cg()->traceRegisterAssignment("Spill candidates for %R (target %R):", virtReg,
            _registerFile[targetRegister]);
    else
        self()->cg()->traceRegisterAssignment("Spill candidates for %R:", virtReg);

    for (i = 0; i < NumBestRegisters; i++) {
        bestRegisters[i] = NULL;
        bestDistances[i] = 0;
    }

    // Identify all spillable candidates of the appropriate register type.
    //
    for (i = first; i <= last; i++) {
        // Don't consider registers that can't be assigned.
        //
        if (_registerFile[i]->getState() == TR::RealRegister::Locked) {
            continue;
        }

        realReg = self()->getRealRegister((TR::RealRegister::RegNum)i);

        if (realReg->getState() == TR::RealRegister::Assigned) {
            candidates[numCandidates++] = realReg->getAssignedRegister();
            if (targetRegister == i) {
                if (useRegisterInterferences
                    && (interference & (1 << (i - 1)))) // TODO:AMD64: Use the proper mask value
                    bestRegisters[InterferingTarget] = realReg->getAssignedRegister();
                else
                    bestRegisters[NonInterferingTarget] = realReg->getAssignedRegister();
            }
        }
    }

    if (numCandidates == 0) {
        // If we are trying to find a suitable spill register for a virtual that currently occupies a
        // register required in a register dependency, there may not be any suitable spill
        // candidates if all available real registers are requested in the register dependency.  In
        // such a case, where our virtual need not be in a register across the dependency, choose the
        // virtual itself as a spill candidate.
        //
        TR_ASSERT_FATAL(considerVirtAsSpillCandidate,
            "freeBestGPRegister(): could not find any GPR spill candidates for %s\n",
            self()->getDebug()->getName(virtReg));

        bestRegister = virtReg;
    }

    // From all the spillable candidates identified, choose the most appropriate based on
    // its rematerialisation value and its proximity to the current instruction.
    //
    TR::RealRegister::RegNum registerNumber;
    for (cursor = currentInstruction->getPrev(); cursor; cursor = cursor->getPrev()) {
        if (cursor->getOpCodeValue() == TR::InstOpCode::proc)
            break;

        if (numCandidates == 0)
            break;

        if (distance > FREE_BEST_REGISTER_SEARCH_DISTANCE)
            break;

        if (cursor->getOpCodeValue() == TR::InstOpCode::fence) {
            // Don't walk past the start of the super (extended) block.
            // This is primarily for the non-linear register assigner because
            // the linear RA won't even have values live beyond the start of the
            // super block
            TR::Node *node = cursor->getNode();
            if (node->getOpCodeValue() == TR::BBStart && !node->getBlock()->isExtensionOfPreviousBlock())
                break;
        }

        if (cursor->getOpCodeValue() == TR::InstOpCode::fence)
            continue;

        for (i = 0; i < numCandidates; i++) {
            registerNumber = toRealRegister(candidates[i]->getAssignedRegister())->getRegisterNumber();

            // Look for case where we come across the dependency reference for
            // the target register and the desired real register is still one
            // of the remaining candidates.
            //
            if (virtReg->getAssociation() != TR::RealRegister::NoReg && cursor->dependencyRefsRegister(virtReg)) {
                for (j = 0; j < numCandidates; ++j) {
                    realReg = toRealRegister(candidates[j]->getAssignedRegister());
                    if (realReg->getRegisterNumber() == virtReg->getAssociation()) {
                        bestRegister = candidates[j];
                        self()->cg()->setRegisterAssignmentFlag(TR_ByAssociation);
                        goto done; // Rude exit
                    }
                }
            }

            interferes = interference & (1 << (registerNumber - 1)); // TODO:AMD64: Use the proper mask value

            if (cursor->refsRegister(candidates[i])) {
                if (distance > FREE_BEST_REGISTER_MINIMUM_CANDIDATE_DISTANCE) {
                    TR_RematerializationInfo *info
                        = candidates[i]->isDiscardable() ? candidates[i]->getRematerializationInfo() : NULL;

                    if (enableRematerialisation && info && info->isActive()) {
                        if (info->isRematerializableFromMemory() || info->isRematerializableFromAddress()) {
                            if (interferes)
                                j = BestInterferingDiscardableMemory;
                            else if (byteRegisterInterference && registerNumber <= TR::RealRegister::Last8BitGPR)
                                j = BestMayInterfereDiscardableMemory;
                            else
                                j = BestNonInterferingDiscardableMemory;
                        } else {
                            TR_ASSERT(candidates[i]->getRematerializationInfo()->isRematerializableFromConstant(),
                                "freeBestGPRegister => unknown rematerialisable register type!");
                            if (interferes)
                                j = BestInterferingDiscardableConstant;
                            else if (byteRegisterInterference && registerNumber <= TR::RealRegister::Last8BitGPR)
                                j = BestMayInterfereDiscardableConstant;
                            else
                                j = BestNonInterferingDiscardableConstant;
                        }

                        if (debug("dumpRemat")) {
                            diagnostic("---> Identified %s rematerialisation spill "
                                       "candidate %s at instruction %s in %s\n",
                                self()->getDebug()->toString(info), self()->getDebug()->getName(candidates[i]),
                                self()->getDebug()->getName(currentInstruction), comp->signature());
                        }
                    } else {
                        if (useRegisterInterferences) {
                            if (interferes)
                                j = BestInterfering;
                            else if (byteRegisterInterference && registerNumber <= TR::RealRegister::Last8BitGPR)
                                j = BestMayInterfere;
                            else
                                j = BestNonInterfering;
                        } else {
                            j = BestNonInterfering;
                        }
                    }

                    bestRegisters[j] = candidates[i];
                    bestDistances[j] = distance;
                    bestType = j;
                    if (useRegisterInterferences && (bestRegisters[j] == bestRegisters[InterferingTarget]))
                        bestDistances[InterferingTarget] = distance;
                    else if (bestRegisters[j] == bestRegisters[NonInterferingTarget])
                        bestDistances[NonInterferingTarget] = distance;
                }

                bestRegister = candidates[i];
                bestDistance = distance;
                candidates[i] = candidates[--numCandidates];
            }
        }
        distance++;
    }

    // Sort out the remaining candidates
    //
    for (i = numCandidates - 1; i >= 0; i--) {
        registerNumber = toRealRegister(candidates[i]->getAssignedRegister())->getRegisterNumber();
        interferes = interference & (1 << (registerNumber - 1)); // TODO:AMD64: Use the proper mask value

        TR_RematerializationInfo *info
            = candidates[i]->isDiscardable() ? candidates[i]->getRematerializationInfo() : NULL;

        if (enableRematerialisation && info && info->isActive()) {
            if (candidates[i]->getRematerializationInfo()->isRematerializableFromMemory()
                || candidates[i]->getRematerializationInfo()->isRematerializableFromAddress()) {
                if (interferes)
                    j = BestInterferingDiscardableMemory;
                else if (byteRegisterInterference && registerNumber <= TR::RealRegister::Last8BitGPR)
                    j = BestMayInterfereDiscardableMemory;
                else
                    j = BestNonInterferingDiscardableMemory;
            } else {
                if (interferes)
                    j = BestInterferingDiscardableConstant;
                else if (byteRegisterInterference && registerNumber <= TR::RealRegister::Last8BitGPR)
                    j = BestMayInterfereDiscardableConstant;
                else
                    j = BestNonInterferingDiscardableConstant;
            }
        } else {
            if (useRegisterInterferences) {
                if (interferes)
                    j = BestInterfering;
                else if (byteRegisterInterference && registerNumber <= TR::RealRegister::Last8BitGPR)
                    j = BestMayInterfere;
                else
                    j = BestNonInterfering;
            } else {
                j = BestNonInterfering;
            }
        }

        bestRegister = bestRegisters[j] = candidates[i];
        bestDistance = bestDistances[j] = distance;
        bestType = j;
        if (useRegisterInterferences && bestRegisters[j] == bestRegisters[InterferingTarget])
            bestDistances[InterferingTarget] = distance;
        else if (bestRegisters[j] == bestRegisters[NonInterferingTarget])
            bestDistances[NonInterferingTarget] = distance;
    }

    if (bestType >= 0) {
        for (i = 0; i < NumBestRegisters; i++) {
            if (bestRegisters[i])
                self()->cg()->traceRegisterAssignment("   (best %s %R at distance %d)", bestRegisters[i],
                    bestRegisterTypes[i], bestDistances[i]);
        }

        // See if there is a candidate with higher priority close enough to the
        // farthest candidate to be better.
        // Ignore candidates that are less than half the distance to the
        // farthest candidate.
        //
        for (i = 0; i < bestType; i++) {
            if (bestDistances[i]
                && (bestDistance - bestDistances[i]) < freeBestRegisterSignificantDistances[i][bestType]
                && (bestDistance - bestDistances[i]) < bestDistances[i]) {
                bestRegister = bestRegisters[i];
                bestDistance = bestDistances[i];
                bestType = i;
                break;
            }
        }
    }

done:

    // Set bestDiscardableRegister if the chosen register is discardable.
    //
    TR::Register *bestDiscardableRegister
        = (bestRegister->isDiscardable() && bestRegister->getRematerializationInfo()->isActive()) ? bestRegister : NULL;

    TR::RealRegister *best = toRealRegister(bestRegister->getAssignedRegister());
    TR::Instruction *instr = NULL;

    if (virtReg->getKind() == TR_VMR) {
        vmrSpillOpcode = TR::InstOpCode::KMOVWMaskMem;
        vmrStoreSize = 2;

        if (cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512BW)) {
            vmrSpillOpcode = TR::InstOpCode::KMOVQMaskMem;
            vmrStoreSize = 8;
        }
    }

    if (enableRematerialisation && bestDiscardableRegister) {
        TR_RematerializationInfo *info = bestDiscardableRegister->getRematerializationInfo();

        if (info->isRematerializableFromMemory()) {
            TR::MemoryReference *tempMR = generateX86MemoryReference(info->getSymbolReference(), self()->cg());

            if (info->isIndirect()) {
                TR_ASSERT(info->getBaseRegister()->getAssignedRegister(),
                    "base register %s of dependent rematerialisable register %s must be assigned\n",
                    self()->getDebug()->getName(info->getBaseRegister()),
                    self()->getDebug()->getName(bestDiscardableRegister));

                tempMR->setBaseRegister(info->getBaseRegister()->getAssignedRegister());
            }

            if (info->getDataType() == TR_RematerializableFloat) {
                instr = generateRegMemInstruction(currentInstruction, TR::InstOpCode::MOVSSRegMem, best, tempMR,
                    self()->cg());
            } else {
                instr = TR::TreeEvaluator::insertLoadMemory(0, best, tempMR, info->getDataType(), self()->cg(),
                    currentInstruction);
            }
        } else if (info->isRematerializableFromAddress()) {
            TR::MemoryReference *tempMR = generateX86MemoryReference(info->getSymbolReference(), self()->cg());
            instr = generateRegMemInstruction(currentInstruction, TR::InstOpCode::LEARegMem(), best, tempMR,
                self()->cg());
        } else {
            if (info->getDataType() == TR_RematerializableFloat) {
                TR::MemoryReference *tempMR
                    = generateX86MemoryReference(self()->cg()->findOrCreate4ByteConstant(currentInstruction->getNode(),
                                                     static_cast<int32_t>(info->getConstant())),
                        self()->cg());
                instr = generateRegMemInstruction(currentInstruction, TR::InstOpCode::MOVSSRegMem, best, tempMR,
                    self()->cg());
            } else {
                instr = TR::TreeEvaluator::insertLoadConstant(0, best, info->getConstant(), info->getDataType(),
                    self()->cg(), currentInstruction);
            }
        }

        self()->cg()->traceRAInstruction(instr);
        if (comp->getDebug())
            comp->getDebug()->addInstructionComment(instr, "$REMAT");

        info->setRematerialized();
        bestDiscardableRegister->setAssignedRegister(NULL);

        if (debug("dumpRemat")) {
            if (info->isIndirect())
                diagnostic("---> Spilling %s rematerialisable register %s (type %d, base %s)\n",
                    self()->getDebug()->toString(info), self()->getDebug()->getName(bestDiscardableRegister),
                    info->getDataType(), self()->getDebug()->getName(info->getBaseRegister()));
            else
                diagnostic("---> Spilling %s rematerialisable register %s (type %d)\n",
                    self()->getDebug()->toString(info), self()->getDebug()->getName(bestDiscardableRegister),
                    info->getDataType());
        }
    } else {
        bool containsInternalPointer = false;
        if (bestRegister->containsInternalPointer())
            containsInternalPointer = true;

        TR_BackingStore *location = NULL;
        int32_t offset = 0;
        if ((bestRegister->getKind() == TR_FPR)) {
            if (bestRegister->getBackingStorage()) {
                // If there is backing storage associated with a register, it means the
                // backing store wasn't returned to the free list and it can be used.
                //
                location = bestRegister->getBackingStorage();
            } else {
                location = self()->cg()->allocateSpill(bestRegister->isSinglePrecision() ? 4 : 8, false, &offset);
            }
        } else if ((bestRegister->getKind() == TR_VRF)) {
            if (bestRegister->getBackingStorage()) {
                // If there is backing storage associated with a register, it means the
                // backing store wasn't returned to the free list and it can be used.
                //
                location = bestRegister->getBackingStorage();
            } else {
                int32_t size = self()->cg()->comp()->target().cpu.supportsAVX() ? 32 : 16;
                size = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F) ? 64 : size;
                location = self()->cg()->allocateSpill(size, false, &offset);
            }
        } else if ((bestRegister->getKind() == TR_VMR)) {
            if (bestRegister->getBackingStorage()) {
                // If there is backing storage associated with a register, it means the
                // backing store wasn't returned to the free list and it can be used.
                //
                location = bestRegister->getBackingStorage();
            } else {
                location = self()->cg()->allocateSpill(vmrStoreSize, false, &offset);
            }
        } else {
            if (containsInternalPointer) {
                if (bestRegister->getBackingStorage()) {
                    // If there is backing storage associated with a register, it means the
                    // backing store wasn't returned to the free list and it can be used.
                    //
                    location = bestRegister->getBackingStorage();
                } else {
                    location = self()->cg()->allocateInternalPointerSpill(bestRegister->getPinningArrayPointer());
                }
            } else {
                if (bestRegister->getBackingStorage()) {
                    // If there is backing storage associated with a register, it means the
                    // backing store wasn't returned to the free list and it can be used.
                    //
                    location = bestRegister->getBackingStorage();
                    location->setMaxSpillDepth(self()->cg()->getCurrentPathDepth());
                    if (self()->cg()->getDebug())
                        self()->cg()->traceRegisterAssignment("find or create free backing store (%p) for %s with "
                                                              "initial max spill depth of %d and adding to list\n",
                            location, self()->cg()->getDebug()->getName(bestRegister),
                            self()->cg()->getCurrentPathDepth());
                } else {
                    location
                        = self()->cg()->allocateSpill(static_cast<int32_t>(TR::Compiler->om.sizeofReferenceAddress()),
                            bestRegister->containsCollectedReference(), &offset);
                    location->setMaxSpillDepth(self()->cg()->getCurrentPathDepth());
                    if (self()->cg()->getDebug())
                        self()->cg()->traceRegisterAssignment("find or create free backing store (%p) for %s with "
                                                              "initial max spill depth of %d and adding to list\n",
                            location, self()->cg()->getDebug()->getName(bestRegister),
                            self()->cg()->getCurrentPathDepth());
                }
            }
        }

        if (self()->cg()->getUseNonLinearRegisterAssigner()) {
            TR_ASSERT(bestRegister, "did not find bestRegister");
            TR_ASSERT(self()->cg()->getSpilledRegisterList(), "no spilled reg list allocated");

            if (self()->getDebug())
                self()->cg()->traceRegisterAssignment("adding %s to the spilledRegisterList)\n",
                    self()->getDebug()->getName(bestRegister));

            self()->cg()->getSpilledRegisterList()->push_front(bestRegister);
        }

        TR::MemoryReference *tempMR = generateX86MemoryReference(location->getSymbolReference(), offset, self()->cg());
        bestRegister->setBackingStorage(location);
        TR_ASSERT(offset == 0 || offset == 4, "assertion failure");
        bestRegister->setIsSpilledToSecondHalf(offset > 0);

        bestRegister->setAssignedRegister(NULL);
        self()->cg()->getSpilledIntRegisters().push_front(bestRegister);

        TR::InstOpCode::Mnemonic op;
        if (bestRegister->getKind() == TR_FPR) {
            op = (bestRegister->isSinglePrecision()) ? TR::InstOpCode::MOVSSRegMem
                                                     : (self()->cg()->getXMMDoubleLoadOpCode());
        } else if (bestRegister->getKind() == TR_VRF) {
            op = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VMOVDQUYmmMem
                                                                  : TR::InstOpCode::MOVDQURegMem;
            op = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F) ? InstOpCode::VMOVDQUZmmMem
                                                                                             : op;
        } else if (bestRegister->getKind() == TR_VMR) {
            op = vmrSpillOpcode;
        } else {
            op = TR::InstOpCode::LRegMem();
        }
        instr = new (self()->cg()->trHeapMemory())
            TR::X86RegMemInstruction(currentInstruction, op, best, tempMR, self()->cg());

        self()->cg()->traceRegFreed(bestRegister, best);
        self()->cg()->traceRAInstruction(instr);
    }

    if (enableRematerialisation)
        self()->cg()->deactivateDependentDiscardableRegisters(bestRegister);

    best->setAssignedRegister(NULL);
    best->setState(TR::RealRegister::Free);

    return best;
}

#if defined(_MSC_VER) && !defined(DEBUG)
#pragma optimize("g", on)
#endif

TR::RealRegister *OMR::X86::Machine::reverseGPRSpillState(TR::Instruction *currentInstruction,
    TR::Register *spilledRegister, TR::RealRegister *targetRegister, TR_RegisterSizes requestedRegSize)
{
    TR::Compilation *comp = self()->cg()->comp();

    if (targetRegister == NULL) {
        targetRegister = self()->findBestFreeGPRegister(currentInstruction, spilledRegister, requestedRegSize);
        if (targetRegister == NULL) {
            targetRegister = self()->freeBestGPRegister(currentInstruction, spilledRegister, requestedRegSize);
        }
    }

    TR_BackingStore *location = spilledRegister->getBackingStorage();

    // If the virtual register has better spill placement info, see if the spill
    // can be moved to later in the instruction stream
    //
    if (self()->cg()->enableBetterSpillPlacements()) {
        if (spilledRegister->hasBetterSpillPlacement()) {
            TR::Instruction *betterInstruction
                = self()->cg()->findBetterSpillPlacement(spilledRegister, targetRegister->getRegisterNumber());
            if (betterInstruction) {
                self()->cg()->setRegisterAssignmentFlag(TR_HasBetterSpillPlacement);
                currentInstruction = betterInstruction;
            }
        }

        self()->cg()->removeBetterSpillPlacementCandidate(targetRegister);
    }

    if (self()->cg()->getUseNonLinearRegisterAssigner()) {
        self()->cg()->getSpilledRegisterList()->remove(spilledRegister);
    }

    self()->cg()->getSpilledIntRegisters().remove(spilledRegister);

    if (self()->cg()->enableRematerialisation() && spilledRegister->getKind() != TR_VMR) {
        self()->cg()->reactivateDependentDiscardableRegisters(spilledRegister);

        // A store is not necessary if the register can be rematerialised.
        //
        if (spilledRegister->getRematerializationInfo()
            && spilledRegister->getRematerializationInfo()->isRematerialized()) {
            if (debug("dumpRemat")) {
                diagnostic("---> Avoiding storing %s rematerializable register %s to memory in %s\n",
                    self()->getDebug()->toString(spilledRegister->getRematerializationInfo()),
                    self()->getDebug()->getName(spilledRegister), comp->signature());
            }

            return targetRegister;
        }
    }

    TR::MemoryReference *tempMR = generateX86MemoryReference(location->getSymbolReference(),
        spilledRegister->isSpilledToSecondHalf() ? 4 : 0, self()->cg());
    TR::Instruction *instr = NULL;

    if (spilledRegister->getKind() == TR_FPR) {
        instr = new (self()->cg()->trHeapMemory()) TR::X86MemRegInstruction(currentInstruction,
            spilledRegister->isSinglePrecision() ? TR::InstOpCode::MOVSSMemReg : TR::InstOpCode::MOVSDMemReg, tempMR,
            targetRegister, self()->cg());

        // Do not add a freed spill slot back onto the free list if the list is locked.
        // This is to enforce re-use of the same spill slot for a virtual register
        // while assigning non-linear control flow regions.
        //
        self()->cg()->freeSpill(location, spilledRegister->isSinglePrecision() ? 4 : 8,
            spilledRegister->isSpilledToSecondHalf() ? 4 : 0);
        if (!self()->cg()->isFreeSpillListLocked()) {
            spilledRegister->setBackingStorage(NULL);
        }
    } else if (spilledRegister->getKind() == TR_VRF) {
        TR::InstOpCode::Mnemonic movOpcode;
        movOpcode = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VMOVDQUMemYmm
                                                                     : TR::InstOpCode::MOVDQUMemReg;
        movOpcode = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)
            ? InstOpCode::VMOVDQUMemZmm
            : movOpcode;
        instr = new (self()->cg()->trHeapMemory())
            TR::X86MemRegInstruction(currentInstruction, movOpcode, tempMR, targetRegister, self()->cg());

        // Do not add a freed spill slot back onto the free list if the list is locked.
        // This is to enforce re-use of the same spill slot for a virtual register
        // while assigning non-linear control flow regions.
        //
        int32_t size = self()->cg()->comp()->target().cpu.supportsAVX() ? 32 : 16;
        size = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F) ? 64 : size;
        self()->cg()->freeSpill(location, size, 0);
        if (!self()->cg()->isFreeSpillListLocked()) {
            spilledRegister->setBackingStorage(NULL);
        }
    } else if (spilledRegister->getKind() == TR_VMR) {
        TR::InstOpCode::Mnemonic opcode = TR::InstOpCode::KMOVWMemMask;
        int32_t spillSize = 2;

        if (cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512BW)) {
            opcode = TR::InstOpCode::KMOVQMemMask;
            spillSize = 8;
        }

        instr = new (self()->cg()->trHeapMemory())
            TR::X86MemRegInstruction(currentInstruction, opcode, tempMR, targetRegister, self()->cg());

        // Do not add a freed spill slot back onto the free list if the list is locked.
        // This is to enforce re-use of the same spill slot for a virtual register
        // while assigning non-linear control flow regions.
        //
        self()->cg()->freeSpill(location, spillSize, 0);
    } else {
        instr = new (self()->cg()->trHeapMemory()) TR::X86MemRegInstruction(currentInstruction,
            TR::InstOpCode::SMemReg(), tempMR, targetRegister, self()->cg());
        // Do not add a freed spill slot back onto the free list if the list is locked.
        // This is to enforce re-use of the same spill slot for a virtual register
        // while assigning non-linear control flow regions.
        //
        self()->cg()->freeSpill(location, static_cast<int32_t>(TR::Compiler->om.sizeofReferenceAddress()),
            spilledRegister->isSpilledToSecondHalf() ? 4 : 0);
        if (!self()->cg()->isFreeSpillListLocked()) {
            spilledRegister->setBackingStorage(NULL);
        }
    }

    self()->cg()->traceRAInstruction(instr);

    return targetRegister;
}

void OMR::X86::Machine::coerceGPRegisterAssignment(TR::Instruction *currentInstruction, TR::Register *virtualRegister,
    TR::RealRegister::RegNum registerNumber, bool coerceToSatisfyRegDeps)
{
    TR::RealRegister *targetRegister = _registerFile[registerNumber];
    TR::RealRegister *currentAssignedRegister = virtualRegister->getAssignedRealRegister();
    TR::Instruction *instr = NULL;

    TR::InstOpCode::Mnemonic movOpcode = TR::InstOpCode::MOVRegReg();

    if (virtualRegister->getKind() == TR_VMR) {
        movOpcode = cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512BW)
            ? TR::InstOpCode::KMOVQMaskMask
            : TR::InstOpCode::KMOVWMaskMask;
    }

    if (targetRegister->getState() == TR::RealRegister::Free) {
        if (currentAssignedRegister == NULL) {
            if (virtualRegister->getTotalUseCount() != virtualRegister->getFutureUseCount()) {
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterReloaded);
                self()->reverseGPRSpillState(currentInstruction, virtualRegister, targetRegister);
            }
        } else {
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, movOpcode,
                currentAssignedRegister, targetRegister, self()->cg());
            currentAssignedRegister->setState(TR::RealRegister::Free);
            currentAssignedRegister->setAssignedRegister(NULL);
        }

        if (self()->cg()->enableBetterSpillPlacements())
            self()->cg()->removeBetterSpillPlacementCandidate(targetRegister);

        self()->cg()->traceRegAssigned(virtualRegister, targetRegister);
        if (instr)
            self()->cg()->traceRAInstruction(instr);
    } else if (targetRegister->getState() == TR::RealRegister::Blocked
        || targetRegister->getState() == TR::RealRegister::Assigned) {
        TR::Register *currentTargetVirtual = targetRegister->getAssignedRegister();

        self()->cg()->setRegisterAssignmentFlag(TR_IndirectCoercion);

        // Cannot XCHG vector mask registers
        if (currentAssignedRegister != NULL && currentTargetVirtual->getKind() != TR_VMR) {
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                TR::InstOpCode::XCHGRegReg(), currentAssignedRegister, targetRegister, self()->cg());

            if (targetRegister->getState() == TR::RealRegister::Assigned)
                currentAssignedRegister->setState(TR::RealRegister::Assigned, currentTargetVirtual->isPlaceholderReg());
            currentAssignedRegister->setAssignedRegister(currentTargetVirtual);
            currentTargetVirtual->setAssignedRegister(currentAssignedRegister);
            self()->cg()->traceRegAssigned(currentTargetVirtual, currentAssignedRegister);
            self()->cg()->traceRAInstruction(instr);
        } else {
            TR::RealRegister *candidate = self()->findBestFreeGPRegister(currentInstruction, currentTargetVirtual);

            if (candidate) {
                if (self()->cg()->enableBetterSpillPlacements())
                    self()->cg()->removeBetterSpillPlacementCandidate(candidate);
            } else {
                // A spill is needed, either to satisfy the coercion, or to free up a second
                // register whence the virtual currently occupying the target may be moved,
                // i.e. an indirect coercion.
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterSpilled);
                candidate = self()->freeBestGPRegister(currentInstruction, currentTargetVirtual, TR_WordReg,
                    registerNumber, coerceToSatisfyRegDeps);
            }

            if ((targetRegister != candidate) && (candidate != currentTargetVirtual)) {
                instr = new (self()->cg()->trHeapMemory())
                    TR::X86RegRegInstruction(currentInstruction, movOpcode, targetRegister, candidate, self()->cg());
                currentTargetVirtual->setAssignedRegister(candidate);
                candidate->setAssignedRegister(currentTargetVirtual);
                candidate->setState(targetRegister->getState());
                self()->cg()->traceRegAssigned(currentTargetVirtual, candidate);
                self()->cg()->traceRAInstruction(instr);
                self()->cg()->resetRegisterAssignmentFlag(TR_RegisterSpilled); // the spill (if any) has been traced
            }

            if (virtualRegister->getTotalUseCount() != virtualRegister->getFutureUseCount()) {
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterReloaded);
                self()->reverseGPRSpillState(currentInstruction, virtualRegister, targetRegister);
            }
        }

        if (targetRegister->getState() == TR::RealRegister::Blocked) {
            if (self()->cg()->enableBetterSpillPlacements())
                self()->cg()->removeBetterSpillPlacementCandidate(targetRegister);
        }

        self()->cg()->resetRegisterAssignmentFlag(TR_IndirectCoercion);
        self()->cg()->traceRegAssigned(virtualRegister, targetRegister);
    }

    targetRegister->setState(TR::RealRegister::Assigned, virtualRegister->isPlaceholderReg());
    targetRegister->setAssignedRegister(virtualRegister);
    virtualRegister->setAssignedRegister(targetRegister);
    virtualRegister->setAssignedAsByteRegister(false);
}

void OMR::X86::Machine::coerceXMMRegisterAssignment(TR::Instruction *currentInstruction, TR::Register *virtualRegister,
    TR::RealRegister::RegNum regNum, bool coerceToSatisfyRegDeps)
{
    TR::RealRegister *targetRegister = _registerFile[regNum];
    TR::RealRegister *currentAssignedRegister = virtualRegister->getAssignedRealRegister();
    TR::Instruction *instr = NULL;

    if (targetRegister->getState() == TR::RealRegister::Free) {
        if (currentAssignedRegister == NULL) {
            if (virtualRegister->getTotalUseCount() != virtualRegister->getFutureUseCount()) {
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterReloaded);
                self()->reverseGPRSpillState(currentInstruction, virtualRegister, targetRegister);
            }
        } else {
            if (virtualRegister->getKind() == TR_VRF) {
                TR::InstOpCode::Mnemonic movOpcode;
                movOpcode = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VMOVDQUYmmYmm
                                                                             : TR::InstOpCode::MOVDQURegReg;
                movOpcode = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)
                    ? InstOpCode::VMOVDQUZmmZmm
                    : movOpcode;

                instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, movOpcode,
                    currentAssignedRegister, targetRegister, self()->cg());
            } else if (virtualRegister->isSinglePrecision()) {
                instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                    TR::InstOpCode::MOVAPSRegReg, currentAssignedRegister, targetRegister, self()->cg());
            } else {
                instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                    TR::InstOpCode::MOVAPDRegReg, currentAssignedRegister, targetRegister, self()->cg());
            }
            currentAssignedRegister->setState(TR::RealRegister::Free);
            currentAssignedRegister->setAssignedRegister(NULL);
        }
        self()->cg()->removeBetterSpillPlacementCandidate(targetRegister);

        self()->cg()->traceRegAssigned(virtualRegister, targetRegister);
        if (instr)
            self()->cg()->traceRAInstruction(instr);
    } else if (targetRegister->getState() == TR::RealRegister::Blocked) {
        TR::Register *currentTargetVirtual = targetRegister->getAssignedRegister();

        self()->cg()->setRegisterAssignmentFlag(TR_IndirectCoercion);
        if (currentAssignedRegister != NULL) {
            // Exchange the contents of two XMM registers without an XCHG instruction.
            //
            TR::InstOpCode::Mnemonic xchgOp = TR::InstOpCode::bad;
            if (virtualRegister->getKind() == TR_FPR && virtualRegister->isSinglePrecision()) {
                xchgOp = TR::InstOpCode::XORPSRegReg;
            } else if (virtualRegister->getKind() == TR_VRF) {
                xchgOp = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VXORPDYmmYmm
                                                                          : TR::InstOpCode::XORPDRegReg;
                xchgOp = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)
                    ? InstOpCode::VPXORDZmmZmm
                    : xchgOp;
            } else {
                xchgOp = TR::InstOpCode::XORPDRegReg;
            }

            self()->cg()->traceRegAssigned(currentTargetVirtual, currentAssignedRegister);
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, xchgOp,
                currentAssignedRegister, targetRegister, self()->cg());
            self()->cg()->traceRAInstruction(instr);
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, xchgOp,
                targetRegister, currentAssignedRegister, self()->cg());
            self()->cg()->traceRAInstruction(instr);
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, xchgOp,
                currentAssignedRegister, targetRegister, self()->cg());
            self()->cg()->traceRAInstruction(instr);
            currentAssignedRegister->setState(TR::RealRegister::Blocked);
            currentAssignedRegister->setAssignedRegister(currentTargetVirtual);
            currentTargetVirtual->setAssignedRegister(currentAssignedRegister);
        } else {
            TR::RealRegister *candidate
                = self()->findBestFreeGPRegister(currentInstruction, currentTargetVirtual, TR_QuadWordReg);

            if (candidate) {
                self()->cg()->removeBetterSpillPlacementCandidate(candidate);
            } else {
                // A spill is needed, either to satisfy the coercion, or to free up a second
                // register whence the virtual currently occupying the target may be moved,
                // i.e. an indirect coercion.
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterSpilled);
                candidate = self()->freeBestGPRegister(currentInstruction, currentTargetVirtual, TR_QuadWordReg, regNum,
                    coerceToSatisfyRegDeps);
            }

            if (targetRegister != candidate) {
                if (virtualRegister->getKind() == TR_VRF) {
                    TR::InstOpCode::Mnemonic movOpcode;
                    movOpcode = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VMOVDQUYmmYmm
                                                                                 : TR::InstOpCode::MOVDQURegReg;
                    movOpcode = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)
                        ? InstOpCode::VMOVDQUZmmZmm
                        : movOpcode;
                    instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, movOpcode,
                        targetRegister, candidate, self()->cg());
                } else if (currentTargetVirtual->isSinglePrecision()) {
                    instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                        TR::InstOpCode::MOVAPSRegReg, targetRegister, candidate, self()->cg());
                } else {
                    instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                        TR::InstOpCode::MOVAPDRegReg, targetRegister, candidate, self()->cg());
                }
                candidate->setState(TR::RealRegister::Blocked);
                candidate->setAssignedRegister(currentTargetVirtual);
                currentTargetVirtual->setAssignedRegister(candidate);
                self()->cg()->traceRegAssigned(currentTargetVirtual, candidate);
                self()->cg()->traceRAInstruction(instr);
                self()->cg()->resetRegisterAssignmentFlag(TR_RegisterSpilled); // the spill (if any) has been traced
            }

            if (virtualRegister->getTotalUseCount() != virtualRegister->getFutureUseCount()) {
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterReloaded);
                self()->reverseGPRSpillState(currentInstruction, virtualRegister, targetRegister);
            }
        }

        self()->cg()->removeBetterSpillPlacementCandidate(targetRegister);
        self()->cg()->resetRegisterAssignmentFlag(TR_IndirectCoercion);
        self()->cg()->traceRegAssigned(virtualRegister, targetRegister);
    } else if (targetRegister->getState() == TR::RealRegister::Assigned) {
        TR::Register *currentTargetVirtual = targetRegister->getAssignedRegister();

        self()->cg()->setRegisterAssignmentFlag(TR_IndirectCoercion);
        if (currentAssignedRegister != NULL) {
            TR::InstOpCode::Mnemonic xchgOp = TR::InstOpCode::bad;
            if (virtualRegister->getKind() == TR_FPR && virtualRegister->isSinglePrecision()) {
                xchgOp = TR::InstOpCode::XORPSRegReg;
            } else if (virtualRegister->getKind() == TR_VRF) {
                xchgOp = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VXORPDYmmYmm
                                                                          : TR::InstOpCode::XORPDRegReg;
                xchgOp = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)
                    ? InstOpCode::VPXORDZmmZmm
                    : xchgOp;
            } else {
                xchgOp = TR::InstOpCode::XORPDRegReg;
            }

            self()->cg()->traceRegAssigned(currentTargetVirtual, currentAssignedRegister);
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, xchgOp,
                currentAssignedRegister, targetRegister, self()->cg());
            self()->cg()->traceRAInstruction(instr);
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, xchgOp,
                targetRegister, currentAssignedRegister, self()->cg());
            self()->cg()->traceRAInstruction(instr);
            instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, xchgOp,
                currentAssignedRegister, targetRegister, self()->cg());
            self()->cg()->traceRAInstruction(instr);
            currentAssignedRegister->setState(TR::RealRegister::Assigned, currentTargetVirtual->isPlaceholderReg());
            currentAssignedRegister->setAssignedRegister(currentTargetVirtual);
            currentTargetVirtual->setAssignedRegister(currentAssignedRegister);
        } else {
            TR::RealRegister *candidate
                = self()->findBestFreeGPRegister(currentInstruction, currentTargetVirtual, TR_QuadWordReg);
            if (candidate) {
                self()->cg()->removeBetterSpillPlacementCandidate(candidate);
            } else {
                // A spill is needed, either to satisfy the coercion, or to free up a second
                // register whence the virtual currently occupying the target may be moved,
                // i.e. an indirect coercion.
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterSpilled);
                candidate = self()->freeBestGPRegister(currentInstruction, currentTargetVirtual, TR_QuadWordReg, regNum,
                    coerceToSatisfyRegDeps);
            }

            if (targetRegister != candidate) {
                if (virtualRegister->getKind() == TR_VRF) {
                    TR::InstOpCode::Mnemonic movOpcode;
                    movOpcode = self()->cg()->comp()->target().cpu.supportsAVX() ? InstOpCode::VMOVDQUYmmYmm
                                                                                 : TR::InstOpCode::MOVDQURegReg;
                    movOpcode = self()->cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)
                        ? InstOpCode::VMOVDQUZmmZmm
                        : movOpcode;
                    instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction, movOpcode,
                        targetRegister, candidate, self()->cg());
                } else if (currentTargetVirtual->isSinglePrecision()) {
                    instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                        TR::InstOpCode::MOVAPSRegReg, targetRegister, candidate, self()->cg());
                } else {
                    instr = new (self()->cg()->trHeapMemory()) TR::X86RegRegInstruction(currentInstruction,
                        TR::InstOpCode::MOVAPDRegReg, targetRegister, candidate, self()->cg());
                }
                candidate->setState(TR::RealRegister::Assigned, currentTargetVirtual->isPlaceholderReg());
                candidate->setAssignedRegister(currentTargetVirtual);
                currentTargetVirtual->setAssignedRegister(candidate);
                self()->cg()->traceRegAssigned(currentTargetVirtual, candidate);
                self()->cg()->traceRAInstruction(instr);
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterSpilled); // the spill (if any) has been traced
            }

            if (virtualRegister->getTotalUseCount() != virtualRegister->getFutureUseCount()) {
                self()->cg()->setRegisterAssignmentFlag(TR_RegisterReloaded);
                self()->reverseGPRSpillState(currentInstruction, virtualRegister, targetRegister);
            }
        }

        self()->cg()->resetRegisterAssignmentFlag(TR_IndirectCoercion);
        self()->cg()->traceRegAssigned(virtualRegister, targetRegister);
    }

    targetRegister->setState(TR::RealRegister::Assigned, virtualRegister->isPlaceholderReg());
    targetRegister->setAssignedRegister(virtualRegister);
    virtualRegister->setAssignedRegister(targetRegister);
    virtualRegister->setAssignedAsByteRegister(false);
}

void OMR::X86::Machine::swapGPRegisters(TR::Instruction *currentInstruction, TR::RealRegister::RegNum regNum1,
    TR::RealRegister::RegNum regNum2)
{
    TR::RealRegister *realReg1 = self()->getRealRegister(regNum1);
    TR::RealRegister *realReg2 = self()->getRealRegister(regNum2);
    TR::Instruction *instr = new (self()->cg()->trHeapMemory())
        TR::X86RegRegInstruction(currentInstruction, TR::InstOpCode::XCHGRegReg(), realReg1, realReg2, self()->cg());

    TR::Register *virtReg1 = realReg1->getAssignedRegister();
    TR::Register *virtReg2 = realReg2->getAssignedRegister();

    virtReg1->setAssignedRegister(realReg2);
    virtReg2->setAssignedRegister(realReg1);
    realReg1->setAssignedRegister(virtReg2);
    realReg2->setAssignedRegister(virtReg1);

    self()->cg()->traceRegAssigned(virtReg1, realReg2);
    self()->cg()->traceRegAssigned(virtReg2, realReg1);
    self()->cg()->traceRAInstruction(instr);
}

void OMR::X86::Machine::coerceGPRegisterAssignment(TR::Instruction *currentInstruction, TR::Register *virtualRegister,
    TR_RegisterSizes requestedRegSize)
{
    TR::RealRegister *candidate;
    if ((candidate = self()->findBestFreeGPRegister(currentInstruction, virtualRegister, requestedRegSize)) == NULL) {
        self()->cg()->setRegisterAssignmentFlag(TR_RegisterSpilled);
        candidate = self()->freeBestGPRegister(currentInstruction, virtualRegister, requestedRegSize);
    }

    if (virtualRegister->getTotalUseCount() != virtualRegister->getFutureUseCount()) {
        self()->cg()->setRegisterAssignmentFlag(TR_RegisterReloaded);
        self()->reverseGPRSpillState(currentInstruction, virtualRegister, candidate);
    }

    if (self()->cg()->enableBetterSpillPlacements())
        self()->cg()->removeBetterSpillPlacementCandidate(candidate);

    candidate->setState(TR::RealRegister::Assigned, virtualRegister->isPlaceholderReg());
    candidate->setAssignedRegister(virtualRegister);
    virtualRegister->setAssignedRegister(candidate);
    virtualRegister->setAssignedAsByteRegister(false);

    self()->cg()->traceRegAssigned(virtualRegister, candidate);
}

void OMR::X86::Machine::setGPRWeightsFromAssociations()
{
    const TR::X86LinkageProperties &linkageProperties = self()->cg()->getProperties();

    for (int i = TR::RealRegister::FirstGPR; i <= TR::RealRegister::LastAssignableGPR; ++i) {
        // Skip non-assignable registers
        //
        if (self()->getRealRegister((TR::RealRegister::RegNum)i)->getState() == TR::RealRegister::Locked)
            continue;

        TR::Register *assocReg = _registerAssociations[i];
        if ((linkageProperties.isPreservedRegister((TR::RealRegister::RegNum)i)
                || linkageProperties.isCalleeVolatileRegister((TR::RealRegister::RegNum)i))
            && _registerFile[i]->getHasBeenAssignedInMethod() == false) {
            if (assocReg) {
                assocReg->setAssociation(i);
            }
            _registerFile[i]->setWeight(IA32_REGISTER_INITIAL_PRESERVED_WEIGHT);
        } else if (assocReg == NULL) {
            _registerFile[i]->setWeight(IA32_REGISTER_BASIC_WEIGHT);
        } else {
            assocReg->setAssociation(i);
            if (assocReg->isPlaceholderReg()) { // placeholder register and is only needed at the specific dependency
                                                // site (usually a killed register on a call)
                                                // so defer this register's weight to that of registers
                                                // where the associated register has a longer life
                _registerFile[i]->setWeight(IA32_REGISTER_PLACEHOLDER_WEIGHT);
            } else {
                _registerFile[i]->setWeight(IA32_REGISTER_ASSOCIATED_WEIGHT);
            }
        }
    }
}

void OMR::X86::Machine::createRegisterAssociationDirective(TR::Instruction *cursor)
{
    TR::Compilation *comp = self()->cg()->comp();
    TR::RegisterDependencyConditions *associations
        = generateRegisterDependencyConditions((uint8_t)0, TR::RealRegister::LastAssignableGPR, self()->cg());

    // Go through the current associations held in the machine and put a copy of
    // that state out into the stream after the cursor
    // so that when the register assigner goes backwards through this point
    // it updates the machine and register association states properly
    //
    for (int i = 0; i < TR::RealRegister::LastAssignableGPR; i++) {
        TR::RealRegister::RegNum regNum = (TR::RealRegister::RegNum)(i + 1);

        // Skip non-assignable registers
        //
        if (self()->getRealRegister(regNum)->getState() == TR::RealRegister::Locked)
            continue;

        associations->addPostCondition(self()->getVirtualAssociatedWithReal(regNum), regNum, self()->cg(), 0, true);
    }

    associations->stopAddingPostConditions();

    new (self()->cg()->trHeapMemory()) TR::Instruction(associations, TR::InstOpCode::assocreg, cursor, self()->cg());
    if (cursor == self()->cg()->getAppendInstruction())
        self()->cg()->setAppendInstruction(cursor->getNext());

    // There's no need to have a virtual appear in more than one TR::InstOpCode::assocreg after
    // its live range has ended.  One is enough.  So we clear out all the dead
    // registers from the associations.
    //
    for (int i = TR::RealRegister::FirstGPR; i <= TR::RealRegister::LastAssignableGPR; i++) {
        TR::Register *virtReg = self()->getVirtualAssociatedWithReal((TR::RealRegister::RegNum)i);
        if (virtReg && !virtReg->isLive())
            self()->setVirtualAssociatedWithReal((TR::RealRegister::RegNum)i, NULL);
    }
}

// TODO:AMD64: Confirm that this is what the weights mean
#define PRESERVED_WEIGHT 0xFF00
#define NONPRESERVED_WEIGHT 0
#define UNUSED_WEIGHT 0xFFFF

void OMR::X86::Machine::initializeRegisterFile(const struct TR::X86LinkageProperties &properties)
{
    int reg;

    // Special pseudo-registers
    //
    _registerFile[TR::RealRegister::NoReg] = NULL;
    _registerFile[TR::RealRegister::ByteReg] = NULL;
    _registerFile[TR::RealRegister::BestFreeReg] = NULL;

    // GPRs
    //
    _registerFile[TR::RealRegister::eax] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
        properties.isPreservedRegister(TR::RealRegister::eax) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
        TR::RealRegister::Free, TR::RealRegister::eax, TR::RealRegister::eaxMask, self()->cg());

    static char *dontUseEBXasGPR = feGetEnv("dontUseEBXasGPR");

    if (!dontUseEBXasGPR) {
        _registerFile[TR::RealRegister::ebx] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
            properties.isPreservedRegister(TR::RealRegister::ebx) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
            TR::RealRegister::Free, TR::RealRegister::ebx, TR::RealRegister::ebxMask, self()->cg());
    } else {
        _registerFile[TR::RealRegister::ebx] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
            UNUSED_WEIGHT, TR::RealRegister::Locked, TR::RealRegister::ebx, TR::RealRegister::ebxMask, self()->cg());
        _registerFile[TR::RealRegister::ebx]->setAssignedRegister(_registerFile[TR::RealRegister::ebx]);
    }

    _registerFile[TR::RealRegister::ecx] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
        properties.isPreservedRegister(TR::RealRegister::ecx) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
        TR::RealRegister::Free, TR::RealRegister::ecx, TR::RealRegister::ecxMask, self()->cg());

    _registerFile[TR::RealRegister::edx] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
        properties.isPreservedRegister(TR::RealRegister::edx) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
        TR::RealRegister::Free, TR::RealRegister::edx, TR::RealRegister::edxMask, self()->cg());

    _registerFile[TR::RealRegister::edi] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
        properties.isPreservedRegister(TR::RealRegister::edi) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
        TR::RealRegister::Free, TR::RealRegister::edi, TR::RealRegister::ediMask, self()->cg());

    _registerFile[TR::RealRegister::esi] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
        properties.isPreservedRegister(TR::RealRegister::esi) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
        TR::RealRegister::Free, TR::RealRegister::esi, TR::RealRegister::esiMask, self()->cg());

    // Platforms that are able to use ebp as a GPR can set the state to Free and
    // clear the assigned register in the CodeGen constructor.
    _registerFile[TR::RealRegister::ebp] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR, UNUSED_WEIGHT,
        TR::RealRegister::Locked, TR::RealRegister::ebp, TR::RealRegister::ebpMask, self()->cg());
    _registerFile[TR::RealRegister::ebp]->setAssignedRegister(_registerFile[TR::RealRegister::ebp]);

    _registerFile[TR::RealRegister::esp] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR, UNUSED_WEIGHT,
        TR::RealRegister::Locked, TR::RealRegister::esp, TR::RealRegister::espMask, self()->cg());
    _registerFile[TR::RealRegister::esp]->setAssignedRegister(_registerFile[TR::RealRegister::esp]);

    _registerFile[TR::RealRegister::vfp] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR, UNUSED_WEIGHT,
        TR::RealRegister::Locked, TR::RealRegister::vfp, TR::RealRegister::noRegMask, self()->cg());
    _registerFile[TR::RealRegister::vfp]->setAssignedRegister(_registerFile[TR::RealRegister::NoReg]);

#ifdef TR_TARGET_64BIT
    for (reg = TR::RealRegister::r8; reg <= TR::RealRegister::LastAssignableGPR; reg++) {
        _registerFile[reg] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_GPR,
            properties.isPreservedRegister((TR::RealRegister::RegNum)reg) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
            TR::RealRegister::Free, (TR::RealRegister::RegNum)reg,
            TR::RealRegister::gprMask((TR::RealRegister::RegNum)reg), self()->cg());
    }
#endif

    // Other register kinds
    //
    for (reg = TR::RealRegister::FirstFPR; reg <= TR::RealRegister::LastFPR; reg++) {
        _registerFile[reg] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_X87,
            properties.isPreservedRegister((TR::RealRegister::RegNum)reg) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
            TR::RealRegister::Free, (TR::RealRegister::RegNum)reg,
            TR::RealRegister::fprMask((TR::RealRegister::RegNum)reg), self()->cg());
    }

    for (reg = TR::RealRegister::FirstXMMR; reg <= TR::RealRegister::LastXMMR; reg++) {
        _registerFile[reg] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_FPR,
            properties.isPreservedRegister((TR::RealRegister::RegNum)reg) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
            TR::RealRegister::Free, (TR::RealRegister::RegNum)reg,
            TR::RealRegister::xmmrMask((TR::RealRegister::RegNum)reg), self()->cg());
    }

    if (cg()->comp()->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F)) {
        for (reg = TR::RealRegister::k0; reg <= TR::RealRegister::k7; reg++) {
            _registerFile[reg] = new (self()->cg()->trHeapMemory()) TR::RealRegister(TR_VMR,
                properties.isPreservedRegister((TR::RealRegister::RegNum)reg) ? PRESERVED_WEIGHT : NONPRESERVED_WEIGHT,
                TR::RealRegister::Free, (TR::RealRegister::RegNum)reg,
                TR::RealRegister::vectorMaskMask((TR::RealRegister::RegNum)reg), self()->cg());
        }
    }
}

uint32_t *OMR::X86::Machine::getGlobalRegisterTable(const struct TR::X86LinkageProperties &property)
{
    uint32_t *allocationOrder = property.getRegisterAllocationOrder();
    for (int i = 0; i < self()->getNumGlobalGPRs() + _numGlobalFPRs; i++) {
        _globalRegisterNumberToRealRegisterMap[i] = allocationOrder[i];
    }
    return _globalRegisterNumberToRealRegisterMap;
}

TR::RegisterDependencyConditions *OMR::X86::Machine::createDepCondForLiveGPRs()
{
    int32_t i, c = 0;

    // Calculate number of register dependencies required.  This step is not really necessary, but
    // it is space conscious.
    //
    for (i = TR::RealRegister::FirstGPR; i <= TR::RealRegister::LastXMMR;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        TR::RealRegister *realReg = self()->getRealRegister((TR::RealRegister::RegNum)i);
        if (realReg->getState() == TR::RealRegister::Assigned || realReg->getState() == TR::RealRegister::Free
            || realReg->getState() == TR::RealRegister::Blocked)
            c++;
    }

    TR::RegisterDependencyConditions *deps = NULL;

    if (c) {
        deps = generateRegisterDependencyConditions(0, c, self()->cg());
        for (i = TR::RealRegister::FirstGPR; i <= TR::RealRegister::LastXMMR;
             i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
            TR::RealRegister *realReg = self()->getRealRegister((TR::RealRegister::RegNum)i);
            if (realReg->getState() == TR::RealRegister::Assigned || realReg->getState() == TR::RealRegister::Free
                || realReg->getState() == TR::RealRegister::Blocked) {
                TR::Register *virtReg;
                if (realReg->getState() == TR::RealRegister::Free) {
                    virtReg
                        = self()->cg()->allocateRegister(i <= TR::RealRegister::LastAssignableGPR ? TR_GPR : TR_FPR);
                    virtReg->setPlaceholderReg();
                } else {
                    virtReg = realReg->getAssignedRegister();
                }
                deps->addPostCondition(virtReg, realReg->getRegisterNumber(), self()->cg());
                if (virtReg->isPlaceholderReg())
                    self()->cg()->stopUsingRegister(virtReg);
                virtReg->incTotalUseCount();
                virtReg->incFutureUseCount();
            }
        }
    }

    return deps;
}

// if calledForDeps == false then this is being called to generate conditions for use in regAssocs
TR::RegisterDependencyConditions *OMR::X86::Machine::createCondForLiveAndSpilledGPRs(
    TR::list<TR::Register *> *spilledRegisterList)
{
    int32_t i, c = 0;

    // Calculate number of register dependencies required.  This step is not really necessary, but
    // it is space conscious.
    //
    int32_t endReg = TR::RealRegister::LastAssignableGPR;
    TR_LiveRegisters *liveFPRs = self()->cg()->getLiveRegisters(TR_FPR);
    TR_LiveRegisters *liveVRFs = self()->cg()->getLiveRegisters(TR_VRF);
    if ((liveFPRs && liveFPRs->getNumberOfLiveRegisters() > 0)
        || (liveVRFs && liveVRFs->getNumberOfLiveRegisters() > 0))
        endReg = TR::RealRegister::LastXMMR;
    for (i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        TR::RealRegister *realReg = self()->getRealRegister((TR::RealRegister::RegNum)i);
        TR_ASSERT(realReg->getState() == TR::RealRegister::Assigned || realReg->getState() == TR::RealRegister::Free
                || realReg->getState() == TR::RealRegister::Locked,
            "cannot handle realReg state %d, (block state is %d)\n", realReg->getState(), TR::RealRegister::Blocked);
        if (realReg->getState() == TR::RealRegister::Assigned)
            c++;
    }

    c += spilledRegisterList ? static_cast<int32_t>(spilledRegisterList->size()) : 0;

    TR::RegisterDependencyConditions *deps = NULL;

    if (c) {
        deps = generateRegisterDependencyConditions(0, c, self()->cg());
        for (i = TR::RealRegister::FirstGPR; i <= endReg;
             i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
            TR::RealRegister *realReg = self()->getRealRegister((TR::RealRegister::RegNum)i);
            if (realReg->getState() == TR::RealRegister::Assigned) {
                TR::Register *virtReg = realReg->getAssignedRegister();
                TR_ASSERT(!spilledRegisterList
                        || !(std::find(spilledRegisterList->begin(), spilledRegisterList->end(), virtReg)
                            != spilledRegisterList->end()),
                    "a register should not be in both an assigned state and in the spilled list\n");
                deps->addPostCondition(virtReg, realReg->getRegisterNumber(), self()->cg());

                virtReg->incTotalUseCount();
                virtReg->incFutureUseCount();
                virtReg->setAssignedRegister(NULL);
                realReg->setAssignedRegister(NULL);
                realReg->setState(TR::RealRegister::Free);
            }
        }

        if (spilledRegisterList) {
            for (auto i = spilledRegisterList->begin(); i != spilledRegisterList->end(); ++i) {
                deps->addPostCondition(*i, TR::RealRegister::SpilledReg, self()->cg());
            }
        }
    }

    return deps;
}

TR::RealRegister **OMR::X86::Machine::captureRegisterFile()
{
    int32_t arraySize = sizeof(TR::RealRegister *) * TR::RealRegister::NumRegisters;

    TR::RealRegister **registerFileClone
        = (TR::RealRegister **)self()->cg()->trMemory()->allocateMemory(arraySize, heapAlloc);

    int32_t endReg = TR::RealRegister::LastXMMR;
    for (int32_t i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        registerFileClone[i]
            = (TR::RealRegister *)self()->cg()->trMemory()->allocateMemory(sizeof(TR::RealRegister), heapAlloc);
        *registerFileClone[i] = *_registerFile[i];
    }

    registerFileClone[TR::RealRegister::vfp]
        = (TR::RealRegister *)self()->cg()->trMemory()->allocateMemory(sizeof(TR::RealRegister), heapAlloc);
    *registerFileClone[TR::RealRegister::vfp] = *_registerFile[TR::RealRegister::vfp];

    return registerFileClone;
}

void OMR::X86::Machine::installRegisterFile(TR::RealRegister **registerFileCopy)
{
    int32_t endReg = TR::RealRegister::LastXMMR;

    // Unlink currently assigned registers from their virtuals.  This must be done
    // before the register file is installed to prevent unintended clobbering.
    //
    for (int32_t i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        TR::Register *assignedVirtReg = _registerFile[i]->getAssignedRegister();
        if (assignedVirtReg != NULL) {
            TR_ASSERT(_registerFile[i]->getState() == TR::RealRegister::Assigned
                    || _registerFile[i]->getState() == TR::RealRegister::Locked,
                "expecting register file register to be either assigned or locked");

            if (_registerFile[i]->getState() == TR::RealRegister::Assigned) {
                assignedVirtReg->setAssignedRegister(NULL);
            }
        }
    }

    // Install register file.
    //
    for (int32_t i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        // Some real register fields are sticky and their contents must be preserved.
        //
        // TODO: this will have to be made smarter to work cross platform.
        //
        bool wasAssigned = _registerFile[i]->getHasBeenAssignedInMethod();

        *_registerFile[i] = *registerFileCopy[i];

        // Copy the sticky bits.
        //
        if (wasAssigned) {
            _registerFile[i]->setHasBeenAssignedInMethod(true);
        }

        // Link captured assigned registers to their virtuals.
        //
        if (_registerFile[i]->getState() == TR::RealRegister::Assigned) {
            _registerFile[i]->getAssignedRegister()->setAssignedRegister(_registerFile[i]);
        }
    }

    *_registerFile[TR::RealRegister::vfp] = *registerFileCopy[TR::RealRegister::vfp];
}

TR::Register **OMR::X86::Machine::captureRegisterAssociations()
{
    int32_t arraySize = sizeof(TR::Register *) * TR::RealRegister::NumRegisters;

    TR::Register **registerAssociationsClone
        = (TR::Register **)self()->cg()->trMemory()->allocateMemory(arraySize, heapAlloc);

    int32_t endReg = TR::RealRegister::LastXMMR;
    for (int32_t i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        if (_registerAssociations[i] != NULL) {
            registerAssociationsClone[i]
                = (TR::Register *)self()->cg()->trMemory()->allocateMemory(sizeof(TR::Register), heapAlloc);
            *registerAssociationsClone[i] = *_registerAssociations[i];
        } else {
            registerAssociationsClone[i] = NULL;
        }
    }

    if (_registerAssociations[TR::RealRegister::vfp] != NULL) {
        registerAssociationsClone[TR::RealRegister::vfp]
            = (TR::Register *)self()->cg()->trMemory()->allocateMemory(sizeof(TR::Register), heapAlloc);
        *registerAssociationsClone[TR::RealRegister::vfp] = *_registerAssociations[TR::RealRegister::vfp];
    } else {
        registerAssociationsClone[TR::RealRegister::vfp] = NULL;
    }

    return registerAssociationsClone;
}

TR::list<TR::Register *> *OMR::X86::Machine::captureSpilledRegistersList()
{
    // TODO: hang a spilled registers list from the machine

    TR_ASSERT(self()->cg()->getSpilledRegisterList(), "expecting an existing spilledRegistersList before capture");

    TR::list<TR::Register *> *srl = new (self()->cg()->trHeapMemory())
        TR::list<TR::Register *>(getTypedAllocator<TR::Register *>(self()->cg()->comp()->allocator()));
    for (auto iter = self()->cg()->getSpilledRegisterList()->begin();
         iter != self()->cg()->getSpilledRegisterList()->end(); ++iter) {
        srl->push_front(*iter);
    }

    return srl;
}

TR::RegisterDependencyConditions *TR_RegisterAssignerState::createDependenciesFromRegisterState(
    TR_OutlinedInstructions *oi)
{
    // Calculate the required number of dependencies.
    //
    TR::Compilation *comp = _machine->cg()->comp();
    OMR::Logger *log = comp->log();
    bool trace = comp->getOption(TR_TraceNonLinearRegisterAssigner);

    int32_t numDeps = 0;
    int32_t i;
    int32_t endReg = TR::RealRegister::LastXMMR;
    for (i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        if (_registerFile[i]->getState() == TR::RealRegister::Assigned)
            numDeps++;
    }

    numDeps += static_cast<int32_t>(_spilledRegistersList->size());

    logprintf(trace, log, "createDependenciesFromRegisterState : %d live registers: %d assigned, %d spilled\n", numDeps,
        numDeps - _spilledRegistersList->size(), _spilledRegistersList->size());

    if (numDeps == 0)
        return NULL;

    TR::RegisterDependencyConditions *deps = generateRegisterDependencyConditions(0, numDeps, _machine->cg());

    TR_RegisterAssignerState *rasAtMerge = oi->getRegisterAssignerStateAtMerge();
    TR_ASSERT(rasAtMerge, "Must have captured register assigner state at merge");

    // Populate assignments from the register file.
    //
    for (i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        TR::RealRegister *realReg = _registerFile[i];
        if (realReg->getState() == TR::RealRegister::Assigned) {
            TR::Register *virtReg = realReg->getAssignedRegister();
            deps->addPostCondition(virtReg, realReg->getRegisterNumber(), _machine->cg());

#if 0
         if (!rasAtMerge->isLive(virtReg) &&
             !oi->findInRegisterUsageList(oi->getOutlinedPathRegisterUsageList(), virtReg))
            {
            TR::list<OMR::RegisterUsage*> *mainlineRUL = oi->getMainlinePathRegisterUsageList();

            if (mainlineRUL)
               {
               for(auto iter = mainlineRUL->begin(); iter != mainlineRUL->end(); ++iter)
                  {
                  if ((*iter)->virtReg == virtReg)
                     {
                     virtReg->decTotalUseCount((*iter)->useCount);

                     logprintf(trace, log, "Adjusting up register use counts of reg %p (fuc=%d:tuc=%d:mergeFuc=%d) by %d\n",
                           (*iter)->virtReg, (*iter)->virtReg->getFutureUseCount(), (*iter)->virtReg->getTotalUseCount(), (*iter)->mergeFuc, (*iter)->useCount);
                     }
                  }
               }
            else
               {
               // skip it?
               }
            }
#endif

            // Because this happens during register assignment the future use needs to be adjusted
            // to account for this new use.  The total use count will be adjusted when this
            // dependency is hung off an instruction.
            //
            virtReg->incFutureUseCount();

            logprintf(trace, log, "   create ASSIGNED dependency: virtual %p -> %s\n", virtReg,
                _machine->getDebug()->getName(realReg));

            bool found = (std::find(_spilledRegistersList->begin(), _spilledRegistersList->end(), virtReg)
                != _spilledRegistersList->end());
            TR_ASSERT(!_spilledRegistersList || !found,
                "a register should not be in both an assigned state and in the spilled list\n");
        }
    }

    // Create spill dependencies from the spilled registers list.
    //
    for (auto iter = _spilledRegistersList->begin(); iter != _spilledRegistersList->end(); ++iter) {
        deps->addPostCondition(*iter, TR::RealRegister::SpilledReg, _machine->cg());

        // Because this happens during register assignment the future use needs to be adjusted
        // to account for this new use.  The total use count will be adjusted when this
        // dependency is hung off an instruction.
        //
        (*iter)->incFutureUseCount();

        logprintf(trace, log, "   create SPILLED dependency: virtual %p -> backing storage %p\n", *iter,
            (*iter)->getBackingStorage());
    }

    return deps;
}

// Captures the current state of the register assigner from the machine.
//
void TR_RegisterAssignerState::capture()
{
    _registerFile = _machine->captureRegisterFile();
    _registerAssociations = _machine->captureRegisterAssociations();
    _spilledRegistersList = _machine->captureSpilledRegistersList();
}

// Installs a previously captured register assigner state into the machine.
//
void TR_RegisterAssignerState::install()
{
    TR_ASSERT(_registerFile && _registerAssociations && _spilledRegistersList,
        "missing captured register assigner state");

    // The captured register file cannot simply replace the initial register
    // file in the machine because of the fact that pointers to real registers
    // (i.e., the elements of the register file itself) may be held at various
    // places.  It is not strictly safe to assume we can change the addresses
    // of the register file at will.
    //
    _machine->installRegisterFile(_registerFile);

    // Pointers internal to the following lists are never held and they can be
    // simply swapped in.
    //
    _machine->setRegisterAssociations(_registerAssociations);
    _machine->cg()->setSpilledRegisterList(_spilledRegistersList);
}

// Determine whether a given virtual register is live within a captured
// register state.
//
bool TR_RegisterAssignerState::isLive(TR::Register *virtReg)
{
    // Check the register file
    //
    int32_t i;
    int32_t endReg = TR::RealRegister::LastXMMR;
    for (i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        if (_registerFile[i]->getState() == TR::RealRegister::Assigned) {
            if (_registerFile[i]->getAssignedRegister() == virtReg) {
                return true;
            }
        }
    }

    // Check the spilled register list
    //
    auto iter = _spilledRegistersList->begin();
    for (; (iter != _spilledRegistersList->end()) && (*iter) != virtReg; ++iter) {
    }

    return (iter != _spilledRegistersList->end()) ? true : false;
}

void TR_RegisterAssignerState::dump()
{
    TR::Compilation *comp = _machine->cg()->comp();
    OMR::Logger *log = comp->log();

    if (comp->getOption(TR_TraceNonLinearRegisterAssigner)) {
        log->prints("\nREGISTER ASSIGNER STATE\n=======================\n\nAssigned Live Registers:\n");

        int32_t i;
        int32_t endReg = TR::RealRegister::LastXMMR;
        for (i = TR::RealRegister::FirstGPR; i <= endReg;
             i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
            if (_registerFile[i]->getState() == TR::RealRegister::Assigned) {
                log->printf("         %s -> %s\n", comp->getDebug()->getName(_registerFile[i]->getAssignedRegister()),
                    comp->getDebug()->getName(_registerFile[i]));
            }
        }

        log->prints("\nSpilled Registers:\n");
        for (auto iter = _spilledRegistersList->begin(); iter != _spilledRegistersList->end(); ++iter)
            log->printf("         %s\n", comp->getDebug()->getName(*iter));

        log->prints("\n=======================\n");
    }
}

void OMR::X86::Machine::adjustRegisterUseCountsUp(TR::list<OMR::RegisterUsage *> *rul, bool adjustFuture)
{
    if (!rul)
        return;

    TR::Compilation *comp = self()->cg()->comp();
    OMR::Logger *log = comp->log();

    for (auto iter = rul->begin(); iter != rul->end(); ++iter) {
        if (comp->getOption(TR_TraceNonLinearRegisterAssigner)) {
            log->printf("Adjusting UP register use counts of reg %p (fuc=%d:tuc=%d:adjustFuture=%d) by %d -> ",
                (*iter)->virtReg, (*iter)->virtReg->getFutureUseCount(), (*iter)->virtReg->getTotalUseCount(),
                adjustFuture, (*iter)->useCount);
        }

        (*iter)->virtReg->incTotalUseCount((*iter)->useCount);

        if (adjustFuture)
            (*iter)->virtReg->incFutureUseCount((*iter)->useCount);

        logprintf(comp->getOption(TR_TraceNonLinearRegisterAssigner), comp->log(), "(fuc=%d:tuc=%d)\n",
            (*iter)->virtReg->getFutureUseCount(), (*iter)->virtReg->getTotalUseCount());
    }
}

void OMR::X86::Machine::adjustRegisterUseCountsDown(TR::list<OMR::RegisterUsage *> *rul, bool adjustFuture)
{
    if (!rul)
        return;

    TR::Compilation *comp = self()->cg()->comp();
    OMR::Logger *log = comp->log();
    bool trace = comp->getOption(TR_TraceNonLinearRegisterAssigner);

    for (auto iter = rul->begin(); iter != rul->end(); ++iter) {
        logprintf(trace, log, "Adjusting DOWN register use counts of reg %p (fuc=%d:tuc=%d:adjustFuture=%d) by %d -> ",
            (*iter)->virtReg, (*iter)->virtReg->getFutureUseCount(), (*iter)->virtReg->getTotalUseCount(), adjustFuture,
            (*iter)->useCount);

        (*iter)->virtReg->decTotalUseCount((*iter)->useCount);

        if (adjustFuture)
            (*iter)->virtReg->decFutureUseCount((*iter)->useCount);

        logprintf(trace, log, "(fuc=%d:tuc=%d)\n", (*iter)->virtReg->getFutureUseCount(),
            (*iter)->virtReg->getTotalUseCount());
    }
}

void OMR::X86::Machine::disassociateUnspilledBackingStorage()
{
    int32_t i;
    int32_t endReg = TR::RealRegister::LastXMMR;
    TR_BackingStore *location = NULL;
    TR::Compilation *comp = self()->cg()->comp();

    for (i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        if (_registerFile[i]->getState() == TR::RealRegister::Assigned) {
            TR::Register *virtReg = _registerFile[i]->getAssignedRegister();
            location = virtReg->getBackingStorage();

            if (location) {
                int32_t size = -1;
                if (virtReg->getKind() == TR_FPR) {
                    if (virtReg->isSinglePrecision()) {
                        size = 4;
                    } else {
                        size = 8;
                    }
                } else if (virtReg->getKind() == TR_VRF) {
                    size = comp->target().cpu.supportsAVX() ? 32 : 16;
                    size = comp->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX512F) ? 64 : size;
                } else {
                    size = static_cast<int32_t>(TR::Compiler->om.sizeofReferenceAddress());
                }
                self()->cg()->freeSpill(location, size, virtReg->isSpilledToSecondHalf() ? 4 : 0);
                virtReg->setBackingStorage(NULL);

                logprintf(comp->getOption(TR_TraceNonLinearRegisterAssigner), comp->log(),
                    "disassociating backing storage %p from assigned virtual %p\n", location, virtReg);
            }
        }
    }
}

void OMR::X86::Machine::purgeDeadRegistersFromRegisterFile()
{
    int32_t i;
    int32_t endReg = TR::RealRegister::LastXMMR;
    for (i = TR::RealRegister::FirstGPR; i <= endReg;
         i = ((i == TR::RealRegister::LastAssignableGPR) ? TR::RealRegister::FirstXMMR : i + 1)) {
        if (_registerFile[i]->getState() == TR::RealRegister::Assigned) {
            TR::Register *virtReg = _registerFile[i]->getAssignedRegister();
            if (virtReg->getFutureUseCount() == 0) {
                virtReg->setAssignedRegister(NULL);
                _registerFile[i]->setAssignedRegister(NULL);
                _registerFile[i]->setState(TR::RealRegister::Free);
            }
        }
    }

#if 0
   // TODO: Remove dead spilled registers.
   //
   for(auto iter = cg()->getSpilledRegisterList().begin(); iter != cg()->getSpilledRegisterList().end(); ++iter)
      {
      if ((*iter)->getFutureUseCount() == 0)
         {
         }
      }
#endif
}

// Retrieve a memory reference handle to a dummy local variable of the specified type.
// If the dummy has not been allocated, allocate it and return the handle.
//
// These reusable temporaries are intended for use whenever a temporary store to a
// memory location is required.

TR::MemoryReference *OMR::X86::Machine::getDummyLocalMR(TR::DataType dt)
{
    if (_dummyLocal[dt] == NULL) {
        _dummyLocal[dt] = self()->cg()->allocateLocalTemp(dt);
    }

    return generateX86MemoryReference(_dummyLocal[dt], self()->cg());
}

// Determine the reverse form of an IA32 FP instruction.
//
TR::InstOpCode::Mnemonic OMR::X86::Machine::fpDetermineReverseOpCode(TR::InstOpCode::Mnemonic op)
{
    switch (op) {
        case TR::InstOpCode::FADDRegReg:
        case TR::InstOpCode::DADDRegReg:
        case TR::InstOpCode::FMULRegReg:
        case TR::InstOpCode::DMULRegReg:
        case TR::InstOpCode::FCOMRegReg:
        case TR::InstOpCode::DCOMRegReg:
            // op is unchanged for commutative instructions
            break;

        case TR::InstOpCode::FDIVRegReg:
            op = TR::InstOpCode::FDIVRRegReg;
            break;
        case TR::InstOpCode::DDIVRegReg:
            op = TR::InstOpCode::DDIVRRegReg;
            break;
        case TR::InstOpCode::FDIVRRegReg:
            op = TR::InstOpCode::FDIVRegReg;
            break;
        case TR::InstOpCode::DDIVRRegReg:
            op = TR::InstOpCode::DDIVRegReg;
            break;

        case TR::InstOpCode::FSUBRegReg:
            op = TR::InstOpCode::FSUBRRegReg;
            break;
        case TR::InstOpCode::DSUBRegReg:
            op = TR::InstOpCode::DSUBRRegReg;
            break;
        case TR::InstOpCode::FSUBRRegReg:
            op = TR::InstOpCode::FSUBRegReg;
            break;
        case TR::InstOpCode::DSUBRRegReg:
            op = TR::InstOpCode::DSUBRegReg;
            break;

        default:
            // no reverse instruction, return original
            break;
    }

    return op;
}

// Determine the pop form of an IA32 FP instruction.
//
TR::InstOpCode::Mnemonic OMR::X86::Machine::fpDeterminePopOpCode(TR::InstOpCode::Mnemonic op)
{
    switch (op) {
        case TR::InstOpCode::FADDRegReg:
        case TR::InstOpCode::DADDRegReg:
            op = TR::InstOpCode::FADDPReg;
            break;
        case TR::InstOpCode::FDIVRegReg:
        case TR::InstOpCode::DDIVRegReg:
            op = TR::InstOpCode::FDIVPReg;
            break;
        case TR::InstOpCode::FDIVRRegReg:
        case TR::InstOpCode::DDIVRRegReg:
            op = TR::InstOpCode::FDIVRPReg;
            break;
        case TR::InstOpCode::FISTMemReg:
            op = TR::InstOpCode::FISTPMem;
            break;
        case TR::InstOpCode::DISTMemReg:
            op = TR::InstOpCode::DISTPMem;
            break;
        case TR::InstOpCode::FSSTMemReg:
            op = TR::InstOpCode::FSSTPMem;
            break;
        case TR::InstOpCode::DSSTMemReg:
            op = TR::InstOpCode::DSSTPMem;
            break;
        case TR::InstOpCode::FMULRegReg:
        case TR::InstOpCode::DMULRegReg:
            op = TR::InstOpCode::FMULPReg;
            break;
        case TR::InstOpCode::FSTMemReg:
            op = TR::InstOpCode::FSTPMemReg;
            break;
        case TR::InstOpCode::DSTMemReg:
            op = TR::InstOpCode::DSTPMemReg;
            break;
        case TR::InstOpCode::FSUBRegReg:
        case TR::InstOpCode::DSUBRegReg:
            op = TR::InstOpCode::FSUBPReg;
            break;
        case TR::InstOpCode::FSUBRRegReg:
        case TR::InstOpCode::DSUBRRegReg:
            op = TR::InstOpCode::FSUBRPReg;
            break;
        case TR::InstOpCode::FCOMRegReg:
        case TR::InstOpCode::DCOMRegReg:
            op = TR::InstOpCode::FCOMPReg;
            break;
        case TR::InstOpCode::FCOMRegMem:
            op = TR::InstOpCode::FCOMPMem;
            break;
        case TR::InstOpCode::DCOMRegMem:
            op = TR::InstOpCode::DCOMPMem;
            break;
        case TR::InstOpCode::FCOMPReg:
            op = TR::InstOpCode::FCOMPP;
            break;
        case TR::InstOpCode::FCOMIRegReg:
        case TR::InstOpCode::DCOMIRegReg:
            op = TR::InstOpCode::FCOMIPReg;
            break;
        case TR::InstOpCode::FSTRegReg:
            op = TR::InstOpCode::FSTPReg;
            break;
        case TR::InstOpCode::DSTRegReg:
            op = TR::InstOpCode::DSTPReg;
            break;

        default:
            // no pop instruction, return original
            break;
    }

    return op;
}

uint32_t OMR::X86::Machine::maxAssignableRegisters()
{
    return TR::RealRegister::LastXMMR - TR::RealRegister::FirstXMMR + 1 + TR::RealRegister::LastAssignableGPR
        - TR::RealRegister::FirstGPR;
}

#if defined(DEBUG)
static void printOneRegisterStatus(OMR::Logger *log, TR_FrontEnd *fe, TR_Debug *debug, TR::RealRegister *reg)
{
    log->prints("                      ");
    debug->printFullRegInfo(log, reg);
}

void OMR::X86::Machine::printGPRegisterStatus(OMR::Logger *log, TR_FrontEnd *fe, TR::RealRegister **registerFile)
{
    log->prints("\n  GP Reg Status:          Register         State        Assigned\n");
    int i;
    for (i = TR::RealRegister::FirstGPR; i <= TR::RealRegister::LastAssignableGPR; i++) {
        printOneRegisterStatus(log, fe, self()->getDebug(), registerFile[i]);
    }
    for (i = TR::RealRegister::FirstXMMR; i <= TR::RealRegister::LastXMMR; i++) {
        printOneRegisterStatus(log, fe, self()->getDebug(), registerFile[i]);
    }

    log->flush();
}

// Dump the FP register stack
//
void OMR::X86::Machine::printFPRegisterStatus(OMR::Logger *log, TR_FrontEnd *fe)
{
    char buf[32];
    char *cursor;
    int32_t i;

    log->prints("\n  FP Reg Status:          Register         State        Assigned      Total Future\n");
    for (i = 0; i < 8; i++) {
        memset(buf, ' ', 25);
        cursor = buf + 17;
        sprintf(cursor, "st%d:", i);
        log->printf("%s [ empty      ]\n", buf);
    }

    log->flush();
}
#endif
